The Greens are horrible on their own merits. Any third party in the US needs to start out saying the voting system must be changed. If they don't, that's a good sign they're a combination of a grift and useful idiots. The Greens rarely talk about it unless someone else brings it up first, and they quickly try to change the subject after mumbling a few things about it.

Another sign is that they don't try to build up support over time from local and state races. Greens occasionally run candidates for state congress, but for the most part, they show up for a Presidential run every 4 years and disappear.

Their historical anti-nuclear stance has exasperated climate change. They held back something that would have been very useful to mass deploy 20-30 years ago (although I do think the economics have changed, and it's no longer the right option for new rollouts). The German wing of the party is currently cheering on the dismantling of perfectly good nuclear reactors in exchange for much, much dirtier sources.

Nader's campaign in 2000 absolutely did torpedo Al Gore (and no, you don't have to convert every Nader voter in Florida to Gore for this to be true). He kept power out of the hands of one of the most genuine public servants to run in recent history, and gave power to a trainwreck of an administration that was 180 degrees away from their stated goals.

Greens need to get serious or fuck off.